Shay Logan also signed a pre-contract earlier this week and he has been joined by Brown - a product of the youth system at Wolverhampton Wanderers - and 23-year-old Taylor. Confirmation of the deals was greeted warmly by Derek McInnes.
"Scott is highly-regarded," said the Aberdeen manager. "We watched him the whole of last season and we feel we've got a more than capable goalkeeper to come in and provide real competition in that area.
"Ash has got a great presence and he's at a great age. He's only 23 but has already played 200 games in League One in England and he's a player we think we can work with and improve. We faced significant competition to get him."